The present invention relates to a control system for an automatic transmission of a vehicle, and particularly to a control system which perform a selection control of a shift position during the start of a vehicle.
During the operation of a vehicle in a traffic congestion, an inconvenience may occur where an acceleration/deceleration shock is increased which degrades driveability when the shift position is set to the 1st position. In order to cope with such an inconvenience, a technique of improving driveability of a vehicle during the operation of the vehicle in a traffic congestion has been disclosed, for example, in Japanese Patent Laid-open No. Hei 7-286664 (herewith xe2x80x9cJP ""664xe2x80x9d). According to the control method disclosed in JP ""664, the shift position is prevented from being shifted to the 1st position when it is determined that the vehicle is operating in a traffic congestion and that the vehicle is not in a hill-climbing condition.
However, the control method of the above related art can not accurately determine whether or not the vehicle is operating in a traffic congestion, and therefore the control method often erroneously determine that the vehicle is operating in a traffic congestion even though the vehicle is actually not operating in a traffic congestion. Accordingly, an inconvenience may occur when the control system of a vehicle unnecessarily prevent the shift position to change to the 1st position, and therefore the intention of the driver cannot be sufficiently reflected to the selected shift position.
An objective of the present invention is to provide a control system for an automatic transmission of a vehicle, which is capable of preventing degradation of driveability of the vehicle during the operation of the vehicle in a traffic congestion, and is capable of accurately reflecting the intention of the driver with respect to a selected shift position.
In order to achieve the above objective, the present invention provides a control system for an automatic transmission of a vehicle. The automatic transmission is operable in a manual operating mode and can be changed according to a shift instruction issued by a driver of the vehicle. The automatic transmission is also operable in an automatic operating mode in which the shift position is automatically selected. The control system comprises a slow running intention detecting means and a starting shift position setting means. The slow running intention detecting means detects a slow running intention of the driver. The starting shift position setting means sets a first shift position to a starting shift position at the time of starting the vehicle when the slow running intention of the driver is not detected by the slow running intention detecting means in the manual operating mode, and sets a second shift position which is lower in transmission gear ratio than the first shift position to the starting shift position when the slow running intention of the driver is detected by the slow running intention detecting means in the manual operating mode.
With this configuration, the first shift position is set to the starting shift position at the time of starting the vehicle when the slow running intention of the driver is not detected in the manual operating mode, and the second shift position which is lower in transmission gear ratio than the first shift position is set to the starting shift position when the slow running intention of the driver is detected in the manual operating mode. Specifically, when the slow running intention of the driver is detected during a traffic congestion, the second shift position which is lower in transmission gear ratio than the first shift position, is set to the starting shift position, while when the slow running of the driver is not detected, the first shift position is set to the starting shift position. As a result, it is possible to prevent degradation of driveability during operating a vehicle in a traffic congestion in accordance with the clear slow running intention of the driver, and to obtain a good accelerating performance by selecting the first speed stage when the slow running intention of the driver is not detected.
The present invention provides another control system for an automatic transmission for a vehicle, comprising shift control means, slow running intention detecting means, slow running intention cancellation detecting means, and control mode selecting means. The slow running intention detecting means detects a slow running intention of the driver, and the slow running intention cancellation detecting means detects the cancellation of the slow running intention of the driver. The control mode selecting means selects a first control mode in which a first shift position is set to a starting shift position used at the time of starting the vehicle when the slow running intention of the driver is not detected by the slow running intention detecting means, and selects a second control mode in which a second shift position which is lower in transmission gear ratio than the first shift position is set to the starting shift position when the slow running intention of the driver is detected by the slow running intention detecting means. The control mode selecting means also selects the first control mode when the cancellation of the slow running intention of the driver is detected by the slow running intention cancellation detecting means. The shift control means controls the shift position of the automatic transmission in the control mode selected by the control mode selecting means.
With this configuration, the first control mode in which the first shift position is set to the starting shift position used at the time of starting the vehicle is selected, when the slow running intention of the driver is not detected, and the second control mode in which the second shift position which is lower in transmission gear ratio than the first shift position is set to the starting shift position is selected when the slow running intention of the driver is detected. Further, the first control mode is selected also when the cancellation of the slow running intention of the driver is detected. Specifically, when the slow running intention of the driver is detected during running in a traffic congestion, the second shift position which is lower in transmission gear ratio than the first shift position is set to the starting shift position, while when the slow running of the driver is not detected or the cancellation of the slow running intention is detected, the first shift position is set to the starting shift position. As a result, it is possible to prevent degradation of driveability during the operation of a vehicle in a traffic congestion in accordance with the clear slow running intention of the driver, and to obtain a good accelerating performance by selecting the first speed stage when the slow running intention of the driver is not detected or the cancellation of the slow running intention is detected.
Preferably, the slow running intention cancellation detecting means determines that the slow running intention of the driver is cancelled in at least one of the following cases: a case where a depressing rate of an accelerator pedal operated by the driver becomes greater than a predetermined rate; a case where a running speed of the vehicle becomes equal to or greater than a predetermined vehicle speed; a case where the selection of the first shift position is instructed by the driver; and a case where the selection of a third shift position which is lower in transmission gear ratio than the second shift position is instructed by the driver.
With this configuration, it is determined that the slow running intention of the driver is cancelled in at least one of the following cases: the case where the depressing rate of an accelerator pedal operated by the driver becomes greater than a predetermined rate, the case where the running speed of the vehicle becomes equal to or greater than a predetermined vehicle speed, the case where the selection of the first shift position is instructed by the driver, and the case where the selection of a third shift position which is lower in transmission gear ratio than the second shift position is instructed by the driver. Accordingly, it is possible to accurately determine the termination of the traffic congestion (or the vehicle has left the traffic congestion) or the cancellation of the slow running intention based on a clear intention of the driver, to thereby reflect the determination result to the setting of the starting shift position.
Preferably, the automatic transmission is operable in a manual operating mode in which a shift position of the automatic transmission can be changed according to a shift instruction issued by the driver, and the slow running intention detecting means detects the slow running intention of the driver when a shift-up of the automatic transmission is instructed by the driver in the manual operating mode in a condition where the first shift position is selected and a running speed of the vehicle is equal to or less than a predetermined low vehicle speed.
With this configuration, the slow running intention of the driver who drives the vehicle having the automatic transmission operable in the manual operating mode can accurately be detected.